Brian Dunbar
Headquarters, Washington, D.C.
July 9,1991
(Phone: 202/453-1547)
Susie Marucci
Goddard Space Flight Center, Greenbelt, Md.
(Phone: 301/286-7504)
Keith Koehler
Wallops Flight Facility, Wallops Island, Va.
(Phone: 804/824-1579)
RELEASE: 91-108
NASA'S GODDARD SPACE FLIGHT CENTER TO STUDY SOLAR ECLIPSE
NASA will participate in two experiments to study the July
11 solar eclipse from the ground and from space. A new cryogenic
instrument attached to the 3-meter NASA Infrared Telescope
Facility on the summit of Mauna Kea, Hawaii, will test a theory
about the sun's atomic processes, and an X-ray telescope carried
by a sounding rocket, to be launched from White Sands, N.M., will
study the solar corona.
In the infrared experiment, scientists from NASA's Goddard
Space Flight Center, Greenbelt, Md., will use the eclipse as a
unique diagnostic tool to test a theory that solar non-thermal
atomic processes create the infrared emission lines (very bright
regions in an object's spectrum) first observed in the solar
infrared spectrum in the early 1980s.
The experiment, called the 12-Micron Solar Eclipse
Experiment, will focus on emission lines in the infrared region
of the Sun's spectrum using a new cryogenic grating spectrometer
developed by Goddard's Dr. Donald Jennings. Because the origin
of these emission lines is so localized within a very thin layer
of the Sun's atmosphere, some of their aspects can only be
studied during an eclipse, when the moon blocks the
overwhelmingly bright surface of the Sun.
Normally, emission lines would be formed by thermal
processes in the chromosphere, a relatively hot, thin region of
the solar atmosphere just above the Sun's surface. The Goddard
experiment will test an alternative theory that suggests that the
emission lines are produced by atomic processes in a region of
the atmosphere below and much cooler than the chromosphere.
Emission lines formed in that region must have been created by
non-thermal means, the scientists explain.
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Goddard's Dr. Drake Deming, principal investigator for the
experiment, expects that the data his team receives will prove
the atomic-process theory. Deming said, "We
think our experiment will show that these lines are caused by
non-thermal processes."
The eclipse provides a unique opportunity to observe the
chromosphere, which is not normally "seen" by instruments because
of the brightness of the Sun's surface. As the moon's path takes
it across the Sun, it will screen the spectrometer from the
surface radiation and allow scientists to take readings from the
thin chromosphere. The recording will begin about 40 seconds
before the moon begins to block the Sun completely. The images
will be recorded at about 5 frames-per-second until the last
moment the Sun is completely blocked by the moon.
In the X-ray experiment, a NASA-provided Black Brant IX
sounding rocket will carry an X-ray telescope to observe the
Sun's corona (the extended solar atmosphere from which the solar
wind emanates) at the same time solar observers in Mauna Kea are
seeing the total eclipse. The goal of the experiment is to help
scientists understand the physical mechanisms responsible for
coronal heating and dynamics.
The rocket is scheduled to be launched at 1:26 p.m. EDT July
11 from the White Sands Missile Range, N.M. The launch window
runs from 1:16 p.m. to 1:30 p.m. EDT.
This will be the third flight of the payload. Two other
successful flights were conducted from White Sands on Feb. 22,
1991 and Sept. 11, 1989. The payload will be recovered as in the
previous flights.
The two-stage Black Brant IX, one of 15 suborbital launch
vehicles in NASA's sounding rocket fleet, is expected to carry
the payload to an altitude of 151 miles. The solid-fueled
rocket, with payload, is nearly 53 feet tall.
The principal investigator for the mission is Dr. Leon Golub
from the Smithsonian Astrophysical Observatory, Cambridge, Mass.
The project manager is Frank Lau from the NASA Goddard Space
Flight Center's Wallops Flight Facility, Wallops Island, Va.
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